Traction device

Abstract

To improve an efficiency of traction while continuously executing smooth traction in frontward traction of wire in a traction direction.SOLUTION: A first chuck mechanism C1 and a second chuck mechanism C2 are provided in a described order from a front side toward a rear side in a traction direction. A cylinder S and the second chuck mechanism C2 are fixed to a traction device body KH. A first angle α which is an angle between a first tapered surface of first tapered parts C1b1, C1b2 and a wire core W1 of a wire W is smaller than a second angle β which is an angle between a second tapered surface of second tapered parts C2b1, C2b2 and the wire core W1.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a traction device that uses a wire to traction a notch and cleavage jig from rear to front along the traction direction along the axis of an existing buried pipe, cutting the inner wall of the existing pipe along the traction direction to expand the diameter of the existing pipe. [Background technology]

[0002] Conventionally, the wire blade method has been known as a method for replacing an existing pipe with a new existing pipe. In the wire blade method, as shown in Patent Document 1, for example, a wire is fed into the inside of the existing pipe to be replaced, a cutting and expanding tool for cutting and expanding the diameter of the existing pipe is connected to the tip of the wire, and the other end of the wire is pulled by a pulling device, so that the cutting and expanding tool is moved in the pulling direction along the pipe axis inside the existing pipe, and the existing pipe is cut along the pipe axis and expanded in diameter (see Patent Document 1). The wire braiding method disclosed in Patent Document 1 includes a traction device for traction of the wire, which includes a cylinder mechanism. Such a traction device including a cylinder mechanism usually extends and retracts a cylinder shaft in the traction direction, and pulls the wire in the traction direction in a clamped state in which the wire is clamped by a chuck mechanism in accordance with the extension of the cylinder shaft. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5279100 Summary of the Invention [Problem to be solved by the invention]

[0004] In the wire blade method disclosed in the above-mentioned Patent Document 1, a traction device equipped with a cylinder mechanism is shown as a traction device for traction of the wire, but the traction device does not disclose how to traction the wire using the cylinder mechanism. In particular, when the wire is sequentially pulled in a manner in which the wire is clamped by a chuck mechanism or the like every time the cylinder shaft is extended and the clamping of the wire by the chuck mechanism or the like is released every time the cylinder shaft is retracted, the wire may be pulled back in the direction opposite to the pulling direction or the wire may become loose, resulting in a deterioration in the efficiency of the traction. However, the cited document 1 does not disclose this problem, and there is room for improvement from this perspective.

[0005] The present invention has been made in consideration of the above-mentioned problems, and its purpose is to provide a traction device that can improve the efficiency of traction while continuously performing smooth traction when pulling a wire forward in the traction direction. [Means for solving the problem]

[0006] To achieve the above object, a traction device is provided. A towing device that uses a wire to tow a notch and cleavage jig that cuts the inner wall of an existing pipe along the towing direction from rear to front along the pipe axis of the buried existing pipe to expand the diameter of the existing pipe, and its characteristic configuration is as follows: a cylinder having a cylinder shaft that repeats extending and retracting movements along the pulling direction; a first chuck mechanism that is provided to be movable integrally with the cylinder shaft and is switchable between a first clamping position in which the outer peripheral surface of the wire is clamped during the extending movement of the cylinder shaft and a first non-clamping position in which the outer peripheral surface of the wire is not clamped during the retracting movement of the cylinder shaft; a second chuck mechanism that assumes a second non-clamping position in which the first chuck mechanism does not clamp the outer circumferential surface of the wire when the first chuck mechanism is in the first clamping position, and that assumes a second clamping position in which the first chuck mechanism clamps the outer circumferential surface of the wire when the first chuck mechanism is in the first non-clamping position, in the order described from the front to the rear in the pulling direction, The cylinder and the second chuck mechanism are fixed to a towing device body, the first chuck mechanism includes a first chuck base fixed to the cylinder shaft, and a first tapered portion having a first tapered surface that is slidable along a first sliding surface provided on the first chuck base and that has a first tapered surface that gradually reduces in diameter from the front to the rear and has a first outer circumferential surface that surrounds the outer circumferential surface of the wire, and the first clamping position is a position in which the first outer circumferential surface clamps the wire, the second chuck mechanism includes a second chuck base fixed to the traction device body, and a second tapered portion having a second tapered surface that is slidable along a second sliding surface provided on the second chuck base and that has a second tapered surface that gradually reduces in diameter from the front to the rear and has a second outer circumferential surface that surrounds the outer circumferential surface of the wire, and the second clamping position is a position in which the second outer circumferential surface clamps the wire, A first angle, which is the angle between the first tapered surface of the first tapered portion and the wire axis of the wire, is smaller than a second angle, which is the angle between the second tapered surface of the second tapered portion and the wire axis.

[0007] According to the above characteristic configuration, firstly, a first chuck mechanism capable of clamping the wire while pulling it forward in the pulling direction, and a second chuck mechanism which does not clamp the wire when the first chuck mechanism clamps the wire and clamps the wire when the first chuck mechanism is not clamping the wire, are provided in the order described from front to rear in the pulling direction of the wire.Since the second chuck mechanism clamps the wire during the period when the first chuck mechanism is in the first clamping position and pulling the wire forward in the pulling direction and switched to the first non-clamping position, when the first chuck mechanism is in the first non-clamping position, it is possible to prevent the wire from slackening and from being pulled back in the pulling direction. Furthermore, the traction device of the present invention is configured such that a first angle, which is the angle between the first tapered surface of the first chuck mechanism and the wire axis, is smaller than a second angle, which is the angle between the second tapered surface of the second chuck mechanism and the wire axis. This makes it possible to realize a smooth posture change by making relatively small the angle between the wire axis and the first tapered surface, which is required to clamp and pull the wire and to which a relatively large force is applied, thereby preventing the first outer peripheral surface from biting into the wire too much when the first chuck mechanism switches from the first clamping posture to the first non-clamping posture. In other words, it is possible to prevent a situation in which the first outer peripheral surface is too bitten into the wire when the first chuck mechanism switches from the first clamping posture to the first non-clamping posture, making it impossible to switch to the first non-clamping posture, and smooth pulling can be continuously performed. Furthermore, by making the second angle, which is the angle between the second tapered surface of the second chuck mechanism and the wire axis, relatively large, when the wire goes from a pulling state to a pulling stopped state, the second outer surface of the second chuck mechanism quickly moves in the direction of clamping the wire (a direction perpendicular to the pulling direction) to clamp the wire.Therefore, when the wire slackens and attempts to return backward in the pulling direction, the wire can be quickly clamped by the second outer surface, and the amount of return of the wire in the direction opposite to the pulling direction can be sufficiently reduced. As a result, a traction device can be realized that can improve the efficiency of traction while continuously performing smooth traction when the wire is pulled forward in the traction direction.

[0008] Further features of the towing device include: The first angle is a point that is equal to or greater than 5° and equal to or less than 9°.

[0009] The inventors have confirmed that when a wire generally used for towing, having a length of 10 m to 60 m and a diameter of about 20 mm, is towed to cut and expand an existing pipe, the first tapered portion can be prevented from being excessively bitten into the first chuck base when the first chuck mechanism switches from the first clamping position to the first non-clamping position by setting the first angle to 5° to 9°. Incidentally, if the first angle is less than 5°, slippage may occur between the wire and the first tapered surface during towing, making it difficult to perform towing. On the other hand, if the first angle exceeds 9°, there may be cases where the first chuck mechanism cannot smoothly switch from the first clamping position, in which a relatively large force is applied, to the first non-clamping position.

[0010] Further features of the towing device include: The second angle is in the range of 12° to 15°.

[0011] The inventors have confirmed that when the second chuck mechanism switches from the second non-clamping position to the second clamping position, the wire can be clamped by the second outer circumferential surface more quickly by setting the second angle to 12° or more and 15° or less. Since the second chuck mechanism clamps the wire when it is not being pulled, a large clamping force is not applied between the wire and the second outer circumferential surface, but if the second angle exceeds 15°, the second outer circumferential surface may bite into the wire too much.

[0012] Further features of the towing device include: The feature is that a bending prevention jig is provided which is fixed to the towing device body, extends between the first chuck mechanism and the second chuck mechanism in the towing direction, has an inner diameter larger than the outer diameter of the wire, and allows the wire to be inserted therethrough.

[0013] As explained above, when the first chuck mechanism transitions from the first clamping position to the second clamping position, the first outer circumferential surface may bite too hard into the wire, preventing a smooth transition. In this case, when the cylinder shaft retracts with the first outer circumferential surface of the first chuck mechanism engaged with the wire, the second chuck mechanism is in the second clamping position, causing the wire to bend between the first chuck mechanism and the second chuck mechanism. According to the above-described characteristic configuration, a bending prevention jig is provided that extends between the first chuck mechanism and the second chuck mechanism in the pulling direction, has an inner diameter larger than the outer diameter of the wire, and has the wire inserted therein, thereby effectively preventing the wire from bending between the first chuck mechanism and the second chuck mechanism. Furthermore, by providing the bending prevention jig, it may be possible to eliminate the state in which the first outer circumferential surface of the first chuck mechanism is caught in the wire, thereby achieving even smoother pulling.

[0014] Further features of the towing device include: In the pulling direction, a length of the first outer circumferential surface of the first tapered shape portion of the first chuck mechanism is longer than a length of the second outer circumferential surface of the second tapered shape portion of the second chuck mechanism.

[0015] According to the above-mentioned characteristic configuration, the length of the first outer surface of the first tapered portion of the first chuck mechanism is made relatively long, thereby increasing the frictional force generated between the wire and the first outer surface when the wire is pulled, thereby realizing good pulling. Furthermore, the length of the second outer surface of the second tapered portion of the second chuck mechanism is made relatively short, thereby making the second chuck mechanism compact in the direction perpendicular to the pulling direction. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic diagram showing a wire blade construction method for replacing an existing pipe with a new pipe using a traction device according to an embodiment. [Diagram 2] FIG. 2 is an exploded view of the towing device disassembled into its components. [Diagram 3]FIG. 13 is a diagram showing a state in which the first chuck mechanism is in a first non-clamping position and the second chuck mechanism is in a second clamping position, preventing the wire from being pulled back in the pulling direction. [Figure 4] 13 is a diagram showing a state in which the first chuck mechanism is in a first clamping position and the second chuck mechanism is in a second non-clamping position, pulling the wire forward in the pulling direction. FIG. [Diagram 5] FIG. 4 is a detailed view of the first chuck mechanism when in a first non-clamping position. [Figure 6] FIG. 4 is a detailed view of the first chuck mechanism when in a first clamping position. [Figure 7] FIG. 4 is a detailed view of a second chuck mechanism. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] A traction device according to an embodiment of the present invention relates to a traction device that can improve the efficiency of traction while continuously performing smooth traction when pulling a wire forward in a traction direction.

[0018] The traction device 100 according to this embodiment is suitably used in the wire blade method shown in FIG. In the wire blade method, first, as shown in Figure 1(a), a first pit PT1 is formed at one end of the portion of the existing pipe P to be replaced that is buried underground by excavating the ground G and removing the existing pipe P from the excavated portion, and a second pit PT2 is similarly formed at the other end of the portion of the existing pipe P to be replaced.

[0019] 1(b), a traction device 100 that traction the wire W from rear to front in the traction direction (the direction of the arrow Y in FIG. 1) is installed in the first pit PT1, and the base end (the end on the base side of the arrow Y in the traction direction) of the wire W that is installed so as to be towable by the traction device 100 is sent into the inside of the existing pipe P. Note that the tip end (the end on the tip side of the arrow Y in the traction direction) of the wire W after being towed by the traction device 100 is wound around a drum D installed near the first pit PT1 and collected.

[0020] Finally, as shown in Figure 1 (c), a notch and cleavage tool 200 that cuts and cleaves the inner wall of the existing pipe P along the pulling direction is connected to the base end of the wire W, and a new pipe PE made of polyethylene or the like is connected behind the notch and cleavage tool 200 in the pulling direction.The wire W is then pulled by a pulling device 100, and the existing pipe P is replaced with the new pipe PE.

[0021] Now, as a traction device 100, for example, one equipped with a cylinder mechanism is known. However, when the wire W is sequentially pulled in a manner in which the wire W is clamped by a chuck mechanism or the like each time the cylinder shaft is extended and the clamping of the wire W by the chuck mechanism or the like is released each time the cylinder shaft is retracted, the wire W may be pulled back in the direction opposite to the pulling direction or the wire W may become slack, resulting in a deterioration in the efficiency of the traction.

[0022] Therefore, in the traction device 100 according to the embodiment, as shown in FIGS. 2 to 7, a cylinder S having cylinder shafts SC1 and SC2 that repeat extension and retraction movements along the traction direction (the direction of the arrow Y in FIG. 1) is provided, and the cylinder shafts SC1 and SC2 are provided to be movable together with the cylinder shafts SC1 and SC2. During the extension movement of the cylinder shafts SC1 and SC2, the cylinder S has a first clamping posture (the posture shown in FIGS. 4 and 6) in which the outer circumferential surface Wa of the wire W is clamped, and during the retraction movement of the cylinder shafts SC1 and SC2, the cylinder S has a second clamping posture (the posture shown in FIGS. 5 and 6) in which the outer circumferential surface Wa of the wire W is clamped. The wire W is provided with a first chuck mechanism C1 that can be switched between a first non-clamping position (position shown in Figures 3 and 5) in which the wire W does not clamp the outer surface Wa of the wire W, and a second chuck mechanism C2 that can be switched between a second non-clamping position (position shown in Figure 4) in which the wire W does not clamp the outer surface Wa of the wire W when the first chuck mechanism C1 is in the first clamping position, and a second clamping position (position shown in Figure 3) in which the wire W clamps the outer surface Wa of the wire W when the first chuck mechanism C1 is in the first non-clamping position, in the order listed from front to rear in the towing direction (from the tip to the base end of arrow Y in Figures 3 and 4).

[0023] 2, the first chuck mechanism C1 has cylinder connecting parts C1c1, C1c2 for connecting and fixing to the cylinder S, and the second chuck mechanism C2 has body connecting parts C2c1, C2c2 for connecting and fixing to the traction device body KH. The first chuck mechanism C1 is configured such that the cylinder connecting parts C1c1, C1c2 can be screwed and connected to the cylinder shafts SC1, SC2 of the cylinder S by bolts B or the like, and the second chuck mechanism C2 is configured such that the body connecting parts C2c1, C2c2 can be screwed and connected to the traction device body KH by bolts B or the like.

[0024] As shown in Fig. 2, the cylinder S is inserted into the traction device body KH in a state in which the end of the cylinder S on the side opposite to the side on which the cylinder shafts SC1 and SC2 are extended (the rear side in the traction direction: the base end side of the arrow Y in Fig. 2) abuts against the second chuck mechanism C2 in the direction along the cylinder shafts SC1 and SC2. Incidentally, as shown in Fig. 2, the cylinder S includes a pair of first and second gripping parts SB1 and SB2 extending in the direction along the cylinder shafts SC1 and SC2, and is configured so that an operator can carry the cylinder S by gripping the first and second gripping parts SB1 and SB2.

[0025] To further explain the cylinder S, as shown in Figures 3 and 4, the cylinder S has a pair of a first cylinder SA1 and a second cylinder SA2, as well as a first cylinder shaft SC1 that is extended or retracted by the first cylinder SA1, and a second cylinder shaft SC2 that is extended or retracted by the second cylinder SA2. The cylinder S is hydraulically operated and configured to be able to perform extension and retraction movements of the first cylinder shaft SC1 and the second cylinder shaft SC2 by switching between a first state in which oil is supplied through either the first oil flow pipe OH1 or the second oil flow pipe OH2 and oil is collected from the other, and a second state in which oil is supplied through the other and oil is collected from one. Incidentally, a first cylinder connecting portion C1c1 is connected and fixed to the first cylinder shaft SC1, and a second cylinder connecting portion C1c2 is connected and fixed to the second cylinder shaft SC2.

[0026] When the pulling device 100 pulls the wire W, a reaction force is applied backward in the pulling direction (opposite direction indicated by the arrow Y in FIG. 1), and the pulling device 100 may move backward in the pulling direction. In this embodiment, in order to prevent the towing device 100 from moving rearward in the towing direction, a reaction plate HB capable of abutting against the inner wall of the first pit PT1 is provided on the rear side in the towing direction of the towing device body KH. The reaction plate HB is provided with a wire insertion portion HB2 through which the wire W can be inserted, a reaction force receiving portion HB1 which receives the reaction force toward the rear in the towing direction and which can abut against the inner wall of the first pit PT1, and a fixed flange portion HB3 which is connected to the reaction force receiving portion HB1 by welding or the like and which can be fixed to the towing device main body KH by a bolt B or the like.

[0027] As shown in FIGS. 3, 4, 5, and 6, the first chuck mechanism C1 includes first chuck bases C1a1 and C1a2 fixed to the cylinder shafts SC1 and SC2, and first tapered surfaces C1b1y and C1b2y that are slidable along first sliding surfaces C1a1y and C1a2y provided on the first chuck bases C1a1 and C1a2 and gradually reduce in diameter from the front to the rear. The first tapered surfaces C1b1y and C1b2y surround the outer circumferential surface Wa of the wire W. It has first tapered portions C1b1, C1b2 having outer surfaces C1b1x, C1b2x, and the first clamping position is a position in which the first outer surfaces C1b1x, C1b2x clamp the outer peripheral surface Wa of the wire W (shown in Figures 6(a) and (b)), and the first non-clamping position is a position in which the first outer surfaces C1b1x, C1b2x do not clamp the outer peripheral surface Wa of the wire W and can freely slide relative to the outer peripheral surface Wa (shown in Figures 5(a) and (b)). Here, the first chuck base portions C1a1, C1a2 are provided with biasing rubbers GO that bias the first tapered portions C1b1, C1b2 from the front side to the rear side in the pulling direction.

[0028] The first chuck bases C1a1, C1a2 are fixed to the cylinder shafts SC1, SC2 via cylinder connecting parts C1c1, C1c2. More specifically, the first chuck base C1a1 on one side is fixed to the first cylinder shaft SC1 via the first cylinder connecting part C1c1, and the first chuck base C1a2 on the other side is fixed to the second cylinder shaft SC2 via the second cylinder connecting part C1c2. Incidentally, in this embodiment, as shown in Figures 5 and 6, a one-side first tapered portion C1b1 is provided corresponding to the one-side first chuck base C1a1, and the one-side first tapered surface C1b1y slides on the one-side first sliding surface C1a1y, and a other-side first tapered portion C1b2 is provided corresponding to the other-side first chuck base C1a2, and the other-side first tapered surface C1b2y slides on the other-side first sliding surface C1a2y.

[0029] 5 and 6, when the cylinder shafts SC1 and SC2 extend as shown in Fig. 6, the first tapered portions C1b1 and C1b2 move from front to rear in the pulling direction relative to the first chuck bases C1a1 and C1a2 due to a frictional force F2 between the outer peripheral surface Wa of the wire W and the first outer peripheral surfaces C1b1x and C1b2x. As a result, a pressing force F1 is applied from the first chuck bases C1a1 and C1a2 from the outside to the inside in the radial direction of the wire W to the first tapered portions C1b1 and C1b2, and the first tapered portions C1b1 and C1b2 assume a first clamping posture in which the wire W is clamped. 5, when the cylinder shafts SC1 and SC2 retract, the first chuck bases C1a1 and C1a2 move from front to rear in the pulling direction, and the pressing force F1 from the first chuck bases C1a1 and C1a2 to the first tapered portions C1b1 and C1b2 in the wire radial direction from outside to inside is released. At this time, the friction force F2 between the outer peripheral surface Wa of the wire W and the first outer peripheral surfaces C1b1x and C1b2x is reduced, and the first tapered portions C1b1 and C1b2 become slidable relative to the outer peripheral surface Wa of the wire W, so that the first tapered portions C1b1 and C1b2 are positioned within a certain distance from the first chuck bases C1a1 and C1a2 by the biasing force of the biasing rubber GO.

[0030] As shown in Figures 3, 4 or 7, the second chuck mechanism C2 has second chuck bases C2a1, C2a2 fixed to the traction device main body KH, and second tapered portions C2b1, C2b2 having second tapered surfaces C2b1y, C2b2y that are slidable along second sliding surfaces C2a1y, C2a2y provided on the second chuck bases C2a1, C2a2 and that gradually reduce in diameter from the front to the rear, and having second outer surrounding surfaces C2b1x, C2b2x that surround the outer peripheral surface Wa of the wire W, and the second clamping posture is a posture in which the second outer surrounding surfaces C2b1x, C2b2x clamp the wire W, and the second non-clamping posture is a posture in which the second outer surrounding surfaces C2b1x, C2b2x do not clamp the outer peripheral surface Wa of the wire W and are slidable relative to the outer peripheral surface Wa. Here, the second chuck base portions C2a1, C2a2 are provided with biasing rubbers GO that bias the second tapered portions C2b1, C2b2 from the front side to the rear side in the pulling direction.

[0031] The second chuck bases C2a1 and C2a2 are fixed to the towing device body KH via the body connecting parts C2c1 and C2c2. More specifically, the one-side second chuck base C2a1 is fixed to the towing device body KH via the body connecting part C2c1, and the other-side second chuck base C2a2 is fixed to the towing device body KH via the second body connecting part C2c2. Incidentally, in this embodiment, as shown in FIG. 7, a one-side second tapered portion C2b1 is provided corresponding to the one-side second chuck base C2a1, and the one-side second tapered surface C2b1y slides on the one-side second sliding surface C2a1y, and a other-side second tapered portion C2b2 is provided corresponding to the other-side second chuck base C2a2, and the other-side second tapered surface C2b2y slides on the other-side second sliding surface C2a2y.

[0032] When the wire W is pulled from the rear to the front in the pulling direction, the second tapered portions C2b1, C2b2 move from the rear to the front in the pulling direction due to the frictional force between the outer peripheral surface Wa of the wire W and the second outer peripheral surfaces C2b1x, C2b2x. At this time, a biasing force is applied to the second tapered portions C2b1, C2b2 by the biasing rubber GO toward the second chuck bases C2a1, C2a2, so that the second chuck mechanism C2 assumes the second non-clamping posture while being positioned at a substantially constant distance from the second chuck bases C2a1, C2a2. On the other hand, when the pulling of the wire W stops and the wire W starts to move from front to rear in the pulling direction due to its own weight or the like, the second tapered portions C2b1, C2b2 move from front to rear in the pulling direction due to the frictional force between the outer circumferential surface Wa of the wire W and the second outer circumferential surfaces C2b1x, C2b2x. As a result, a pressing force is applied from the second chuck bases C2a1, C2a2 from the outside to the inside in the radial direction of the wire W to the second tapered portions C2b1, C2b2, resulting in a second clamping posture in which the wire W is clamped.

[0033] As described above, by providing the first chuck mechanism C1 and the second chuck mechanism C2, while the first chuck mechanism C1 is in the first clamping position and pulling the wire W forward in the pulling direction and switching to the first non-clamping position, the wire W is clamped by the second chuck mechanism C2. Therefore, when the first chuck mechanism C1 is in the first non-clamping position, the wire W can be prevented from slackening and from being pulled back in the pulling direction.

[0034] Here, in the traction device 100 according to this embodiment, as shown in Figures 3 and 4, a first angle α (for example, preferably 5° or more and 9° or less, and more preferably 7°) which is the angle between the first tapered surface C1b1y, C1b2y of the first tapered portion C1b1, C1b2 and the wire axis W1 of the wire W is configured to be smaller than a second angle β (for example, preferably 12° or more and 15° or less, and more preferably 13.5°) which is the angle between the second tapered surface C2b1y, C2b2y of the second tapered portion C2b1, C2b2 and the wire axis W1. This enables the first chuck mechanism C1 to be smoothly switched from the first clamping position to the first non-clamping position, while the second chuck mechanism C2 quickly clamps the wire W in the second clamping position, thereby reducing the amount of return of the wire W.

[0035] The inventors have confirmed that when a wire W, which is generally used for towing and has a length of 10 m to 60 m and a diameter of about 20 mm, is towed to cut and expand an existing pipe P, the first tapered portions C1b1 and C1b2 can be effectively prevented from being excessively bitten into the first chuck base portions C1a1 and C1a2 when the first chuck mechanism C1 switches from the first clamping position to the first non-clamping position by setting the first angle α to 5° to 9°. Incidentally, if the first angle α is less than 5°, slippage may occur between the wire W and the first tapered surfaces C1b1y and C1b2y during towing, making it impossible to perform good towing. On the other hand, if the first angle α exceeds 9°, there may be cases where the first chuck mechanism C1 cannot smoothly switch from the first clamping position, to which a relatively large force is applied, to the first non-clamping position. It has also been confirmed that when the second chuck mechanism C2 switches from the second non-clamping position to the second clamping position, the wire W can be clamped quickly by setting the second angle β to be between 12° and 15°. Since the second chuck mechanism C2 clamps the wire W when it is not being pulled, a particularly large clamping force is not applied between the wire W and the second outer circumferential surfaces C2b1x, C2b2x, but if the second angle β exceeds 15°, the second outer circumferential surfaces C2b1x, C2b2x may bite too hard into the wire W.

[0036] In addition, in the traction device 100 in this embodiment, in the traction direction, the length of the first outer circumferential surfaces C1b1x, C1b2x of the first tapered shape portions C1b1, C1b2 of the first chuck mechanism C1 is longer than the length of the second outer circumferential surfaces C2b1x, C2b2x of the second tapered shape portions C2b1, C2b2 of the second chuck mechanism C2.

[0037] Furthermore, in the traction device 100 in this embodiment, in order to prevent the wire W from bending between the first chuck mechanism C1 and the second chuck mechanism C2, a bending prevention jig KB is provided which is fixed to the traction device main body KH, extends between the first chuck mechanism C1 and the second chuck mechanism C2 in the traction direction, has an inner diameter larger than the outer diameter of the wire W, and can insert the wire W therethrough.

[0038] [Another embodiment] (1) In the above embodiment, the towing device body KH, the cylinder S, the first chuck mechanism C1, the second chuck mechanism C2, and the reaction plate HB are separable. However, they may be integrally connected to each other by welding or the like.

[0039] (2) In the above characteristic configuration, the cylinder S is exemplified as having a pair of a first cylinder SA1 and a second cylinder SA2, and having a first cylinder axis SC1 that is extended or retracted by the first cylinder SA1, and a second cylinder axis SC2 that is extended or retracted by the second cylinder SA2. However, the cylinder S may include a single cylinder and a cylinder shaft. Furthermore, the cylinder S is not limited to the hydraulic type described above, and various types such as a pneumatic type may be used.

[0040] (3) In the above embodiment, the first tapered portions C1b1, C1b2 of the first chuck mechanism C1 are formed of a pair of members, the one-side first tapered portion C1b1 and the other-side first tapered portion C1b2. However, the first tapered portions C1b1 and C1b2 are not limited to the above-mentioned configuration, and may be made up of three or more members.

[0041] (4) In the above embodiment, a configuration example has been shown in which, in the pulling direction, the length of the first outer circumferential surfaces C1b1x, C1b2x of the first tapered shape portions C1b1, C1b2 of the first chuck mechanism C1 is longer than the length of the second outer circumferential surfaces C2b1x, C2b2x of the second tapered shape portions C2b1, C2b2 of the second chuck mechanism C2. However, without being limited to this embodiment, in the pulling direction, the length of the first outer circumferential surfaces C1b1x, C1b2x of the first tapered shape portions C1b1, C1b2 of the first chuck mechanism C1 may be less than the length of the second outer circumferential surfaces C2b1x, C2b2x of the second tapered shape portions C2b1, C2b2 of the second chuck mechanism C2.

[0042] (5) In the above embodiment, when the first angle α and the second angle β are set to relatively small angles within the above-mentioned angle range, and the first chuck mechanism C1 and the second chuck mechanism C2 are configured to make it difficult for the wire W to become caught, the bending prevention jig KB does not necessarily have to be provided.

[0043] Furthermore, the configurations disclosed in the above embodiments (including other embodiments, the same applies below) can be applied in combination with configurations disclosed in other embodiments, provided that no contradiction arises. Furthermore, the embodiments disclosed in this specification are merely examples, and the embodiments of the present invention are not limited thereto, and can be appropriately modified within the scope that does not deviate from the purpose of the present invention. [Industrial Applicability]

[0044] INDUSTRIAL APPLICABILITY The traction device of the present invention can be effectively used as a device that can improve the efficiency of traction while continuously performing smooth traction when the wire is pulled forward in the traction direction. [Explanation of symbols]

[0045] 100: Traction device 200: Notch and splitting jig C1: First chuck mechanism C1a1, C1a2: First chuck base C1a1y, C1a2y: 1st sliding surface C1b1, C1b2: First tapered section C1b1x, C1b2x: First outer surface C1b1y, C1b2y: First tapered surface C1c1, C1c2: Cylinder connection part C2: Second chuck mechanism C2a1, C2a2: Second chuck base C2a1y, C2a1y: 2nd sliding surface C2b1, C2b2: Second tapered section C2b1x, C2b2x: Second outer surface C2b1y, C2b2y: Second tapered surface C2c1, C2c2: Main body connection part KB: Anti-bending fixture KH: Traction device body P: Existing pipe S: Cylinder SC1, SC2: Cylinder shaft W: Wire W1: Wire axis Wa: Outer surface α: 1st angle β :Second angle

Claims

1. A towing device that uses a wire to tow a notch and cleavage jig that cuts an inner wall of an existing pipe along a towing direction along the pipe axis of the buried existing pipe from rear to front along the towing direction to expand the diameter of the existing pipe, a cylinder having a cylinder shaft that repeats extending and retracting movements along the pulling direction; a first chuck mechanism that is provided to be movable integrally with the cylinder shaft and is switchable between a first clamping position in which the outer peripheral surface of the wire is clamped during the extending movement of the cylinder shaft and a first non-clamping position in which the outer peripheral surface of the wire is not clamped during the retracting movement of the cylinder shaft; a second chuck mechanism that assumes a second non-clamping position in which the first chuck mechanism does not clamp the outer circumferential surface of the wire when the first chuck mechanism is in the first clamping position, and that assumes a second clamping position in which the first chuck mechanism clamps the outer circumferential surface of the wire when the first chuck mechanism is in the first non-clamping position, in the order described from the front to the rear in the pulling direction, The cylinder and the second chuck mechanism are fixed to a towing device body, the first chuck mechanism includes a first chuck base fixed to the cylinder shaft, and a first tapered portion that is slidable along a first sliding surface provided on the first chuck base and has a first tapered surface that gradually reduces in diameter from the front to the rear and has a first outer circumferential surface that surrounds the outer circumferential surface of the wire, and the first clamping posture is a posture in which the first outer circumferential surface clamps the wire, the second chuck mechanism has a second chuck base fixed to the traction device body, and a second tapered portion that is slidable along a second sliding surface provided on the second chuck base and has a second tapered surface that gradually reduces in diameter from the front to the rear and has a second outer circumferential surface that surrounds the outer circumferential surface of the wire, and the second clamping posture is a posture in which the second outer circumferential surface clamps the wire, A traction device, wherein a first angle, which is an angle between the first tapered surface of the first tapered portion and a wire axis of the wire, is smaller than a second angle, which is an angle between the second tapered surface of the second tapered portion and the wire axis.

2. The traction device of claim 1 , wherein the first angle is greater than or equal to 5° and less than or equal to 9°.

3. 3. The towing device according to claim 1 or 2, wherein the second angle is greater than or equal to 12 degrees and less than or equal to 15 degrees.

4. The towing device according to claim 1 or 2, further comprising a bend prevention jig that is fixed to the towing device body, extends between the first chuck mechanism and the second chuck mechanism in the towing direction, has an inner diameter larger than an outer diameter of the wire, and allows the wire to be inserted therethrough.

5. 3. The towing device according to claim 1, wherein in the towing direction, a length of the first outer circumferential surface of the first tapered shape portion of the first chuck mechanism is longer than a length of the second outer circumferential surface of the second tapered shape portion of the second chuck mechanism.

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